Bandwidth Enhancement of SIW Cavity Backed Slot Antenna Using High-Order Radiation Modes

In this study, we investigate bandwidth enhancement in a Substrate Integrated Waveguide (SIW) cavity-backed slot antenna through high-order radiation modes. The design features an SIW cavity resonator with a precisely etched rectangular radiating slot on the top layer. A folded grounded coplanar waveguide feeding system achieves impedance matching for three higher-order modes, each below −10 dB within a shared frequency band. This matching significantly contributes to the overall bandwidth improvement. The optimized antenna exhibits an impressive 1.428 GHz impedance bandwidth, covering 10.197 GHz to 11.625 GHz. The operational bandwidth displays three distinct resonance dips at 10.23 GHz, 10.906 GHz, and 11.325 GHz, with corresponding gain values of 8.116 dBi, 9.224 dBi, and 8.023 dBi. The proposed design boasts advantages like a simple single-layer structure, wideband capability, and high gain, making it suitable for integration into X-band communication systems.